International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
ISSN: 2319:2682
Bridgeless Dual Buck-Boost Converter Fed
BLDC Motor Drive with Power Factor
Correction
Mr Sreekumar M B
PG Scholar, Power Electronics & Drives
EEE Department
MEA Engineering College
Perinthalmanna, Kerala, India
mesreekumarmb@gmail.com
Abstract – BLDC motors are widely using in many of the
industrial applications. Various converter topologies are
used for feeding these BLDC motor drives.In this paper,
a bridgeless configuration of buck boost converter is
proposing. This converter offers good power quality at
the AC mains with a filter performing the power factor
correction. Speed control of the motor drive is
performed by electronic commutation of the inverter
switches. Simulation of this PFC bridgeless buck boost
topology is done in MATLAB and the validity is proved.
Keywords—Discontinous current conduction mode,
Power factor correction,BLDC motor
I. INTRODUCTION
Brushless DC motors have got wide applications
in the field of automobile vehicle technology, hard
disc drives, compressors etc because of their high
starting torque, reliable operation and good efficiency.
Now a days various automobile applications are
satisfied by these cost effective and reliable brushless
technology operated motorsThese motors are actually
permanent magnet AC motors resembling the torquecurrent characteristics of a DC motor. It is a modified
form of Permanent Magnet Synchronous motor in
which the back emf is trapezoidal which is sinusoidal
in case of PMSM motors. Sensor and sensor less
control are employed in BLDC motors, In sensor
based control, the position of the rotor is identified by
the Hall sensors which are provided at 1200 apart.
Since the technology is simple and highly reliable,
BLDC motors are widely selecting in low power
applications.
DC-DC converters are used for feeding these
BLDC motor drives. Apart from the control of input
voltage to the inverter driving motors, they are also
performing the isolation between input and the load
side. Various converter topologies are being used now
a days depending on the requirements. Both bridge
and bridgeless topologies are using, however the
presence of diode bridge along with high value of DC
link capacitor will lead to the reduction of power
factor since the total harmonic distortion
increases.Inverters are employed to supply power to
the BLDC motor which is a three phase inverter.
Ms Divya Sivan
Assistant Professor, EEE Department
MEA Engineering College
Perinthalmanna, Kerala, India
divyachunakara@gmail.com
Voltage source inverters are most commonly using
and the BLDC motor control through electronic
commutation is made possible by controlling the
gating sequence of inverter switches. Apart from these
VSI, CSI and ZSI topologies are also employing.
Power quality issues are of great interest now
adays. Most of the industrial applications are running
with large power quality issues. Filters are usually
provided along with these converters for the
correction of power quality and thereby reducing the
total harmonic distortion level.
The mode of operation of PFC converters are
selected with great importance since it determines the
cost and component ratings. Converters can be
operated in both continuous conduction mode(CCM)
and discontinuous conduction mode(DCM). DCM is
mostly selecting in low power applications. This is
because, for employing CCM it requires two sensors,
one for sensing the inductor current and other for
sensing the capacitor voltage. In DCM there requires
only one sensor to detect the DC link voltage only.
DC link voltage control cannot be selected in high
power applications since it creates high stress on the
switches
II. PROPOSED BRIDGELESS BUCK-BOOST
CONVERTER FEEDING BLDC MOTOR DRIVE
The proposed system consisting of a bridgeless
buck boost converter feeding a BLDC motor drive.
The converter is operating in discontinuous inductor
current mode for reducing the switching stress.An L
filter is used at the input to improve the power quality.
A dual buck boost converter is used in which one
operating during positive half cycle and the other
operating during the negative half cycle. In each of
the half cycles, the DC link capacitor is continuously
feeding the drive through three different modes. A
voltage source inverter is used to provide alternating
stator current to the motor drive. Electronic
commutation is employed for controlling the switches
of inverter so that the speed control of the BLDC
drive can be made possible. Power factor correction is
done by the voltage feedback control of the converter
132
International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
along with the filter operation. The switching stress
will also be evaluated along with the other parameters
so that the design of heat sinks can be done easily.
The circuit is operating in three modes in each of
the half cycles.Lf and Cf are the filter inductance and
capacitance at the input stage. SW1 and Sw2 are the
switches, L1 and L2 are the inductors, D1 and D2 are
the diodes in the dual buck boost converter. The
inverter switches are numbered through S1 to S6 and
the BLDC motor drive employed with hall effect
position (Ha-Hc) sensors are also shown in the circuit.
ISSN: 2319:2682
Mode 1:The switch Sw2 is conducting and as result of
this the inductor charges and the inductor current i L2
increases. The diode Dn completes the circuit. The
previously stored charge in DC link capacitor will be
transferred to the motor. . It is shown in fig 2(a).
Mode 2:During this mode of operation, the switch Sw2
turns off and the energy stored in inductor will be
transferred to the DC link capacitor and the current iL2
will be decreased.. It is shown in fig 2(b).
Mode 3:In this mode none of the switch and the diode
areconducting. The inductor enters into the
discontinuous mode since the inductor current become
zero. The energy stored in the DC link capacitor Cd
will be transferred to the load. The Switch Sw2
conducts again after the complete switching cycle.. It
is shown in fig 2(c).
Fig 1 : Proposed Converter
During this half cycle of operation the switch Sw2 ,
inductor L2 and the diodes Dn, D2 are operated to
transfer energy from input to the load.
III.OPERATION OF DUAL BUCK BOOST
CONVERTER
The converter is a dual buck boost converter
operating in both positive and negative half cycles of
input supply voltage. It is performed in three different
modes in each of the half cycles which is given below.
Operation during the positive half cycle
During this half cycle of operation the switch
Sw1 , inductor L1 and the diodes Dp, D1 are operated to
transfer energy from input to the load.
Fig 2 (a)
Mode 1:The switch Sw1 is conducting and as result of
this the inductor charges and the inductor current iL1
increases. The diode Dp completes the circuit. The
previously stored charge in DC link capacitor will be
transferred to the motor. It is shown in fig 1(a).
Mode 2:During this mode of operation, the switch Sw1
turns off and the energy stored in inductor will be
transferred to the DC link capacitor and the current iL1
will be decreased.. It is shown in fig 1(b).
Mode 3:In this mode none of the switch and the diode
are conducting. The inductor enters into the
discontinuous mode since the inductor current become
zero. The energy stored in the DC link capacitor Cd
will be transferred to the load. The Switch Sw1
conducts again after the complete switching cycle.
Operation during the negative half cycle.. It is shown
in fig 1(c).During this half cycle of operation the
switch Sw1 , inductor L1 and the diodes Dp, D1 are
operated to transfer energy from input to the load.
Operation during the positive half cycle
Fig 2(b)
Fig 2(c)
Fig 2(a) : Mode 1 Fig2 (b): Mode 2 (c):Mode 3
operation of converter during positive half cycle
133
International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
ISSN: 2319:2682
for a rating of output power 350W. The RMS value of
input voltage is 220V.
2√2𝑉𝑠
Vin =
𝜋
=
2√2∗220
𝜋
= 198V
The converter is designed from 50V to 200V
with a nominal voltage of 100V. So the duty cycle
might varies from .2016 to .5026
Fig 3(a)
A) Design of input inductors Li1 and Li2
For a converter operating in crictical
conduction mode the value of Inductance is given by
Li1,2=
Fig 3(b)
𝑅 (1−𝑑∗𝑑)
2𝑓𝑠
The converter operates in very low value od duty
ratio. At minimum duty ratio the converter is
operating at 50V and 90W power.
Li1,2=
𝑉𝑑𝑐𝑚𝑖𝑛∗𝑉𝑑𝑐𝑚𝑖𝑛 (1−𝑑∗𝑑)
𝑃𝑚𝑖𝑛∗2𝑓𝑠
=
50∗50 (1−.2016∗.2016)
90∗2∗20000
= 442.67µH
This can approximately be selected as 300µH. For the
reliable operation in DICM mode 1/10 of this value is
taken. So its value become 30µH.
Fig 3(c)
Fig 3(a) : Mode 1 Fig 3(b):Mode 2 Fig 3(c):Mode 3
operation of converter during negative half cycle
B) Design of DC link capacitor Cd
For designing, the amount of second order harmonic
current flowing through the capacitor should be taken
into consideration.For a nominal value of 100V,
thepermitted ripple in the DC link voltage can be
taken of the order of 3%
Cd =
Id
2𝑤∆𝑉𝑑𝑐
=
Po/Vdc
2𝑤∆𝑉𝑑𝑐
350/10
=
2∗314∗.03∗100
= 1857.7 µF
Therefore the nearest possible value for the DC link
capacitor can be selected as 2200 µF.
C) Design of input filter
A second order low pass LC filter is used to absorb
the higher order harmonics in order to avoid it from
the supply current. The value of capacitor is designed
such that
Fig 3.1 : Waveform representing mode operation in
each half cycle
IV. DESIGN OF CONVERTER,
FILTERPARAMETERS AND INVERTER
SELECTION
The power factor corrected converter is
operating in discontinuous inductor current mode such
that the inductor currents Li1 and Li2 become
discontinuous in a switching period. The BLDC motor
used is of power 250W and the converter is designed
Cmax =
𝐼𝑝𝑒𝑎𝑘 tan(𝛼)
𝜔𝐿∗𝑉𝑝𝑒𝑎𝑘
=
350∗1∗tan 1
220∗220∗1.732∗314
= 401.980 nF
So the value of capacitor selected is 330nF.The
required value of inductance is given by
Lreq = Lf - Ls
Where Lf is the inductance of the filter and Ls is 4-5%
of the base impedance.
Lreq =
1
4𝜋𝜋∗𝑓𝑐∗𝑓𝑐∗𝐶𝑓
1∗220∗220
- 0.04*
314∗350
= 1.57mH
134
International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
So a low pass filter with capacitance 330nF
and inductance 1.6mH is to be selected.
D) Selection of Inverter for feeding BLDC drive
A voltage source inverter is selected to feed
the BLDC motor drive. It is a 6 switch inverter in
which three legs are used to align them as upper and
lower leg switches. One switch from upper and one
from lower are active at a particular instant of time.
The inverter switches are gated such that the stator
voltages should be within the rating of motor selected.
ISSN: 2319:2682
capacitor for 1200 and placed symmetrically at each
phase. Hall effect position sensor is required to
determine the rotor position. Depending upon this, the
gating signals to the inverter switches are produced by
means of a decoder and corresponding switches from
the upper and lower leg are activated to complete the
current flow and thereby actuating the stator
windings.
Fig. shows the case of line current iab drawn
from the DC link capacitor whose values depending
on the VDC voltage along with the emfsean ,ebn,
resistance Ra,Rb and the inductances La,Lb and M.
Table shows the switching sequence of VSI along
with the status of hall effect position sensors.
The frequency of the hall sensors are not
same. Their variation in active states are decoded for
making the following switching sequence. The upper
leg switches should provided with a bootstrap oriented
gate control since the switch is connected in the
higher voltage side.
Fig 4 : Voltage Source Inverter feeding BLDC Motor
V. CONTROL OF POWER FACTOR CORRECTED
BRIDGELESS BUCK BOOST CONVERTER
A) Control of PFC Converter
The converter is operating in DICM mode
and it is being controlled by voltage follower
approach. The PWM signals to the switches Sw1 and
Sw2 are generated by comparing the DC link voltage
with a referenca signal.The reference signal is
generated such that
Vdc*= kv w*
wherekv is the motors voltage constant and w* is the
reference speed. The error signal is generated by
comparing this DC link voltage level with the
reference DC link voltage.
Ve= Vdc*- Vdc
This error signal is given to the PI controller to
produce the control output voltage.This output control
voltage is compared with a sawtooth wave of high
frequency (md) to generate the PWM pulses.
If Vs> 0,
If md<Vcc , then Sw1 ON
If md≥Vcc , then Sw1 OFF
If Vs< 0,
If md<Vcc , then Sw2 ON
If md ≥ Vcc , then Sw2 OFF
Sw1 and Sw2 are the switching signals.
B) Electronic Commutation
Electronic commutation is performed with
proper switching of the VSI switches such that
symmetrical current is taken from the DC link
Fig 5 : Operation of BLDC motor when switch S1 and
S4 are conducting
TABLE 1: Switching states foe achieving electronic
commutation based on hall sensor output signal levels
Hall Signals
Ha Hb Hc
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
S1
0
1
0
0
0
1
0
0
Switching Sequence
S2 S3 S4 S5 S6
0
0
0
0
0
0
0
0
0
1
1
1
0
0
0
0
1
0
0
1
0
0
1
1
0
0
0
1
0
0
1
0
0
1
0
0
0
0
0
0
VI.SIMULATION RESULTS
The performance of proposed BLDC motor
drive is simulated in MATLAB/Simulink environment
using the Sim-Power-System toolbox. The
performance evaluation of theproposed drive is
categorized in terms of performance of BLDC motor,
BL buck boost converter and the achievedpower
quality indices obtained at AC mains. The
parametersassociated with BLDC motor such as
speed,electromagnetic torque and the stator current
135
International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
ISSN: 2319:2682
areanalysed for proper functioning of BLDC motor.
Parameterssuch as supply voltage, supply current, DC
linkvoltage, inductor currents, switch voltages and
switches currents of PFC BL buck boost converter are
evaluated to demonstrate its proper functioning.
Moreover, power quality indices such as PF (Power
Factor), DPF (Displacement Power Factor), CF (Crest
Factor) and THD (Total Harmonics Distortion) of
supply current are analysed for determining power
quality at AC mains.
The simulation results are shown below. The
performance of the motor under two different speeds
are analysed. Satisfactory performances are obtained
from the motor performance analysis. Power quality is
maintained and various simulation results are shown
below.Fig. 6(a) and 6(b) shows simulation result of
the speed and DC link voltage level corresponding to
a reference speed of 1000 rpm.
Fig 7(a): Speed control for a reference speed
of1400 rpm
Fig 7(b) : DC link voltage level at 1400 rpm
Fig 6(a): Speed control for a reference speed of
1000 rpm
Fig 8: Rotor angle positions at a
reference speedof 1400 rpm
Fig 6(b) : DC link voltage level at 1000rpm
Fig. 7(a) and 7(b) shows simulation result of
the speed and DC link voltage level corresponding to
a reference speed of 1400 rpm.Fig 8 gives the rotor
positions at different instants which show that the
motor is running continuously. Fig 9gives the
variation of torque at different angular positions of the
rotor. Fig 10 shows the inverter phase voltage which
is required for running the motor.
Fig 9: Torque of motor at a reference speed
1400 rpm
136
International Journal of Advanced Information Science and Technology (IJAIST)
Vol.30, No.30, October 2014
ISSN: 2319:2682
operating in DICM mode, no need to adopt current
control mode which require more number of sensors
and also an inner current loop.
Future scope includes the introduction of any
isolation network to control the undesired flow of
electric current and a dynamic load change analyser
can be used for detecting rapid load changes..
REFERENCES
Fig 10: Three phase inverter output voltages fed to
stator windings
The power quality at the AC mains can be
checked by analysing the input voltages and currents.
Fig 11 shows the input voltage and current
waveforms.The improvement in the power factor can
be detected from Fig 12, in which it reaches near to
unity from a lower level of 0.66, shows the correction
in power factor.
Fig 11:Input voltage and current waveform
Fig 9 : Power factor after power quality control
VII. CONCLUSION
This paper presents the simulation of
bridgeless dual buck boost converter operating in
DICM, feeding a BLDC motor drive in low power
applications. With this proposed converter the power
quality can be improved at the AC mains. The total
harmonic distortion can be reduced by using a low
pass filter at the input.The power factor can be
improved upto 0.98 with this arrangement. The speed
control of the BLDC motor can be carried out by
varying the DC bus voltage level. Electronic
commutation will leads to the reduction of switching
stress in the inverter. Speed can be controlled by the
variation in DC link voltage. Since converter
[1] Chang Liang Xia, Permanent Magnet Brushless DC Motor
Drives andControls, Wiley Press, Beijing, 2012.
[2] J. Moreno, M. E. Ortuzar and J.W. Dixon, “Energymanagement systemfor a hybrid electric vehicle, using
ultracapacitors and neural networks,”IEEE Trans. Ind. Electron.,
vol.53, no.2, pp. 614- 623, April 2006.
[3] Y. Chen, C. Chiu, Y. Jhang, Z. Tang and R. Liang, “A Driver
for theSingle-Phase Brushless DC Fan Motor with Hybrid Winding
Structure,”IEEE Trans. Ind. Electron., vol.60, no.10, pp.4369-4375,
Oct. 2013.
[4] Xiaoyan Huang, A. Goodman, C. Gerada, Youtong Fang and
Qinfen Lu,“A Single Sided Matrix Converter Drive for a Brushless
DC Motor inAerospace Applications,” IEEE Trans. Ind. Electron.,
vol.59, no.9,pp.3542-3552, Sept. 2012.
[5] Hamid A. Toliyat and Steven Campbell, DSP-based
ElectromechanicalMotion Control, CRC Press, New York, 2004.
[6] P. Pillay and R. Krishnan, “Modeling of permanent magnet
motordrives,” IEEE Trans. Ind. Electron., vol.35, no.4, pp.537-541,
Nov1988.
[7] Limits for Harmonic Current Emissions (Equipment input
current ≤16 Aper phase), International Standard IEC 61000-3-2,
2000
[8] S. Singh and B. Singh, “A Voltage-Controlled PFC Cuk
Converter Based PMBLDCM Drive for Air-Conditioners”, IEEE
Trans. Ind. Appl., vol. 48, no. 2, pp. 832-838, March-April 2012.
[9] B. Singh, B. N. Singh, A. Chandra, K. Al-Haddad, A. Pandey
and D.P. Kothari, “A review of single-phase improved power
quality AC-DC converters,” IEEE Trans. Ind. Electron., vol. 50, no.
5, pp. 962– 981, Oct. 2003.
[10] B. Singh, S. Singh, A. Chandra and K. Al-Haddad,
“Comprehensive Study of Single-Phase AC-DC Power Factor
Corrected Converters With High-Frequency Isolation,” IEEE
Trans. on Industrial Informatics, vol.7, no.4, pp.540-
Sreekumar M B was born in Kottayam,
Kerala, India in 1990. He received B.Tech
degree in electrical and electronics
engineering from Mahathma Gandhi
University, Kerala, India in 2012. He is
qualified as AutoCAD (MEP) Mechanical
Electrical Plumping Design Engineer from
CAD group builders, Trissur, Kerala, India in 2013. He is
currently pursuing M.Tech degree in power electronics and
drives from MEA Engineering College under University of
Calicut, Kerala, India. His area of interest includes power
electronic converters, power quality and electric drives.
Divya Sivan, was born in Kerala, India, in
1988.She received her Bachelor’sdegree in
Electrical and Electronics in 2010 from IEI,
Kolkatta and M.tech in Power Systems in
2012 from VTU, Belgham,India.Now she is
working as an Assistant Professor in MEA
Engineering College, Kerala. Her major interests include on
Power quality control,Power Electronics converters, Power
system stability etc.
137